When I was a 12 C (now its 21 C I thank) we spent probably 55% of the time in the motor pool, 40% of the time doing training (CTT/MOS Trng), and 5% of the time doing post police etc (however that was at Ft. Hood prior to 9/11).
However 21C's don't get many places to go (Hood, FLW, Polk, Hanau GE, and Korea). Better off being a 12B if you want to do stuff like Airborne.
Just my opinion though